Thin-film photovoltaic modules are generally composed of a number of electrically interconnected optoelectronic components. Such components may be optoelectronic devices such as photovoltaic cells and additional optional components such as diodes and other electronic devices. Photovoltaic modules usually also include electrically interconnecting components such as cell-to-cell connectors and busbars.
Multilayer thin-film technologies enable the monolithic integration and interconnection of several optoelectronic components and associated components on a same substrate. This integration is produced in situ using a sequence of layer deposition and scribing techniques. Thin-film optoelectronic or photovoltaic components or devices are essentially composed of a stack of three material layers: a conducting back-contact electrode layer, a semiconductive photovoltaic material layer, also known as the absorber, and another conducting front-contact electrode layer, said front-contact layer usually being transparent. Photovoltaic cells based on semiconductive material, such as Cu(In,Ga)Se2, which is abbreviated CIGS, show a high potential for less expensive solar electricity, lower energy payback time, and improved life-cycle impact compared to traditional wafer-based silicon photovoltaic devices or solar cells.
Compared to wafer-based photovoltaic devices, monolithic photovoltaic modules may have lower costs thanks to reduced material quantities used to form the thin films that form part of the photovoltaic components, reduced labor costs of monolithic integration, and ease of automatic production of large quantities of photovoltaic modules, for example using roll-to-roll manufacturing techniques. Further savings can be obtained by increasing the relative area of the photovoltaic components exposed to light, for example, by reducing the area occupied by front-contact grids that collect current over the photovoltaic cell's front-contact electrode, electrical interconnects between optoelectronic components and busbars. Photovoltaic module production yields may also be increased thanks to a reduction in the number of production steps, for example by reducing the number of scribing operations needed to delineate and structure the interconnects of optoelectronic components in thin-film monolithic photovoltaic modules.
U.S. Pat. No. 7,276,724 describes series-interconnected optoelectronic device modules thanks to the forming of wrap-through vias, for example using laser ablation, and the addition of conductive material to drive current between electrodes as well as to adjacent modules. Wrap-through vias usually require drilling and subsequent metalizing. This requires additional production steps which may add costs and decrease yield. Some of these steps are avoided with the monolithic optoelectronic module production method of WO2011/148346 which describes forming via holes with copper-rich CIGS-type walls derived from partial melting of the absorber layer's CIGS material.
For some applications, there is a need for a thin-film optoelectronic device and a method of forming the same that comprises via holes shaped as line segments and variations thereof.